1. Field of the Invention
The present invention relates generally to microelectromechanical systems (MEMS) and particularly to composite structures or modules integrating at least one MEMS device with a substrate carrying pre-processed electronic circuitry. The invention further relates to methods for fabricating such modules.
2. Description of the Related Art
MEMS devices comprise a class of very small electromechanical devices that combine many of the most desirable aspects of conventional mechanical and solid-state devices while also providing both low insertion losses and high electrical isolation. Unlike a conventional electromechanical device, a MEMS device can be combined with related electronic circuitry. Presently, this is accomplished either by combining the MEMS device and the circuitry in the form of a multi-chip module (MCM) or by monolithically integrating the two. Both have drawbacks. For example, MCM results in large footprints and inferior performance and, although monolithic integration provides reduced size and improved performance, it typically involves extensive compromises in both circuit and MEMS device processing.
U.S. Pat. No. 6,159,385 issued Dec. 12, 2000, and owned by the assignee of the present invention, discloses a low temperature method using an adhesive to bond a MEMS device to an insulating substrate comprising glass or plain silicon. Among other advantages, adhesive bonding avoids the high temperatures associated with processes such as anodic and fusion bonding.